The present invention relates to marine vessels, and more particularly to a vessel provided with collision protection means installed directly on the hull of the vessel.
With the increased transportation of hazardous materials by marine vessels, such as self propelled tankers and/or towed barges, environmental agencies of many countries require the new ships to be constructed with enhanced resistance to impact of the hull or bottom of the vessel, since such an impact can create spillage and result in an environmental disaster.
For example, U.S. Laws require that vessels have double hull construction to provide for empty space in between the oil tanks and the vessel sides and bottom. It is acknowledged that provision of the double hull can effectively protect against minor impacts, but will be ineffective in the case of impact of a more serious nature. During such impacts, a ship carrying environmentally sensitive cargo is frequently struck in its side by another vessel's bow. The striking vessel's bow penetrates the other vessel's side until the kinetic energy of the striking vessel is absorbed. The damaged vessel absorbs collision energy by distortion and mangling actions resulting in destruction of part of the hull. The exterior shell of the ship offers little resistance and most of the collision energy is absorbed by destroying areas of horizontal plating, such as decks and double bottoms. The collision can even result in permanent damage of the ship to the point where the ship could break into two parts.
Various designs have been suggested for improving impact resistance of a ship. One of such solutions is disclosed in my U.S. Pat. No. 5,353,727, issued on Oct. 11, 1994, entitled "Collision Guard For A Vessel". In that patent, the collision guard is disclosed to comprise buoyant modules, each separately secured to a corresponding side wall of the hull through the means of a post and cap attachment. The collision guards are formed with recesses in the top wherein the caps and the posts are located. The caps and load spreading attachment brackets are welded to the side of the ship. The caps capture the posts and prevent them from moving vertically or horizontally.
While this design is workable in many environments, the present invention contemplates provision of an improved device for securing the collision guard to the vessel by providing easy access to the securing means as well as eliminating the need for precise fitting of vertical mating surfaces between the cap and the post. Additional consideration was taken into account that heating and cooling of the steel hull in the area of welding may cause distortion of the attachment structure and the hull.